there are a couple of anime that I could think of at the top of my head:
-Gintama (why did an another anime had to take it's time slot? This is the 2nd time that this happened!)
-Umineko no Naku koro Ni (darn it when it had to end it off at a cliffhanger!)
-Ouran High School Host Club (just because 26 episodes isn't enough)
-Earl and the Fairy
That's all I could come up with in one sitting.

NANA is easily top of my list...but, until Yazawa Ai is able to finish the manga, I don't see that happening.

Skip Beat would be on the list too, along with Full Metal Panic and Ouran. I would love for them to finally adapt the "Heaven's Feel" part of Fate/Stay Night into anime, but I guess that time has passed.

1. SAO - I love this anime, it needs to continue. 'nuff said.
2. Accel World - So much left in this storyline, nothing was wrapped up. Not my favorite main character at all, but the rest of the show is fascinating.
3. Btooom! - Won't be over till they get off the island!
4. Highschool of The Dead - Another of my fav series. What happens after they leave the mansion!?
5. Black Lagoon - Just cause I want more Revy.
6. Vampire Knight - I wanted more at the end.

I would also advise any other fans who are waiting in vain for a third season to simply give up and read the books, I promise you will not regret it.

Besides that I would also like another season of.

1. Martian Successor Nadesico (I am not satisfied with the film sequel, it sucked.)

2. Darker Than Black. (I would personally enjoy a nice prologue for this one.)

3. Angel Beats. (I would love to see Angel Beats rebooted with a bigger budget and double the episodes so that they can develop the characters more and such, kind of like how Kanon initially had a one cour series and was then redone as a two cour that totally blew the first one away.)

4. Rurouni Kenshin. (If only to animate the Revenge arc at long last.)

5. So Ra No Wo To ( I think the world in this anime has a lot of room for expansion and since it was an original project they would be free to get creative with it.)

6. The Pet Girl of Sakurasou. (Mostly because I cannot find any of the translated novels past volume 3, so I can only hope for a second season if I wish to continue the story.)

Btooom! 100% needs a new season i dont think i put it on my earlier post i might off but there is plenty to go on theres still atleast 10 people on the island we need to see them get off the island together <3